The present invention regards the equipment for entering a determined number of correction factors into photographic printing apparatus. Each of the correction factors may assume one of a predetermined number of values.
In photographic printing apparatus, it is necessary to enter values of a number of correction factors such as the density correction factor which may assume any one of the values of -3, -2, -1, 0, +1, +2 or +3, each of these steps of values indicating a change of approximately 35 percent. Similarly correction factors requiring the selection of one of a plurality of values for color correction in the colors blue, green and red are required. In conventional apparatus, a key is provided signifying each correction factor and further an individual key is required for each value of each of these correction factors. In this way the operator may make a visual inspection of the negative and enter correction values corresponding to the particular characteristics of this negative into the apparatus. When the values of all of the correction factors have been entered, a key is depressed which causes the printing process to take place with the so-entered values of the various correction factors.
This type of input arrangement has a number of disadvantages. First of all a great number of input keys is required. For example, for four correction factors each being able to assume seven different values, 28 keys are required. This tends to make the equipment somewhat unwieldy and unreliable. Further, the operator must find the correct keys out of a relatively large key field which requires visual concentration.